Solve for $x$ and $y$ using substitution. ${-2x-5y = 7}$ ${x = -3y-5}$
Solution: Since $x$ has already been solved for, substitute $-3y-5$ for $x$ in the first equation. ${-2}{(-3y-5)}{- 5y = 7}$ Simplify and solve for $y$ $6y+10 - 5y = 7$ $y+10 = 7$ $y+10{-10} = 7{-10}$ ${y = -3}$ Now that you know ${y = -3}$ , plug it back into $\thinspace {x = -3y-5}\thinspace$ to find $x$ ${x = -3}{(-3)}{ - 5}$ $x = 9 - 5$ ${x = 4}$ You can also plug ${y = -3}$ into $\thinspace {-2x-5y = 7}\thinspace$ and get the same answer for $x$ : ${-2x - 5}{(-3)}{= 7}$ ${x = 4}$